bdd0e96d78
A block's value is now its last statement ONLY when that statement is a trailing expression with no `;`. A trailing `;` discards the value, leaving the block void. This makes value-vs-statement explicit and lets the compiler reject "this block was supposed to produce a value". Compiler: - Parser records `Block.produces_value` (last stmt is a no-`;` trailing expression) + `Block.discarded_semi` (the `;` that discarded a value), via `expectSemicolonAfter`. A trailing expression before `}` may now omit its `;` (previously a parse error). Match-arm and else-arm bodies are built value-producing regardless of the arm `;` (arms are exempt — the `;` is an arm terminator). - Lowering: `lowerBlockValue` / the block-expr path / `inferExprType` respect `produces_value`. A value-position block that discards its value is a hard error (`lowerValueBody` for function bodies; the value-context `.block` path for if/else branches, `catch` bodies, value bindings, match arms). Pure-failable `-> !` bodies (value rides the error channel) and a value-if whose branches are void are handled without false errors. - `defer`/`onfail` cleanup bodies lower as statements (void), so a trailing `;` there is fine. Migration (behavior-preserving — output unchanged): - stdlib + ~210 examples: dropped the trailing `;` on value-position last expressions. `format` now ends with an explicit `#insert "return result;"` (it relied on `#insert`-as-block-value, which `;` discards). - Two `main :: () -> s32` examples that relied on the old silent default-return got an explicit trailing `0`. - Rejection snapshots 0412 / 1013 regenerated (their quoted source lines lost a `;`); the diagnostics themselves are unchanged. Docs/tests: specs.md "Block values" section; examples 0040 (rules) + 0041 (rejection); 3 parser unit tests. Filed issue 0066 (pre-existing match-arm negated-literal phi-width quirk, surfaced not caused here). Gates: zig build, zig build test, run_examples.sh -> 343 passed, cross_compile.sh -> 7 passed (also refreshed its stale example names).
34 lines
960 B
Plaintext
34 lines
960 B
Plaintext
// Regression: when a `#jni_call` method returns a type the
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// `Call<T>Method` switch in `emit_llvm.zig` can't dispatch
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// (anything outside void/bool/s32/s64/f32/f64/pointer), the
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// compiler must emit a DIAGNOSTIC at lower time rather than
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// silently producing `LLVMGetUndef` at codegen time. Without
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// this guard, the chess Android touch bug shipped: an
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// unsupported return type silently became `undef` and showed
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// up as garbage arguments downstream.
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//
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// Here we declare a JNI method returning `s8` (jbyte, not yet
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// wired into the call-method switch). The compile must fail
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// with a clear message naming the method + return type.
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#import "modules/std.sx";
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Buf :: #foreign #jni_class("java/nio/ByteBuffer") {
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get :: (self: *Self) -> s8;
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}
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g_should_call : bool = false;
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unused :: (env: *void, b: *Buf) {
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#jni_env(env) {
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_ := b.get();
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}
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}
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main :: () -> s32 {
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if g_should_call {
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unused(null, null);
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}
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0
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}
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